The role of microbial processes in the phosphorus flux regulation between sediments and water

• Published in: Hydrobiologia 1993-03, Vol.253 (1-3), p.218-218
• Main Authors: Sinke, Anja J. C., Cottaar, Francis H. M., Buis, Kerst, Keizer, Peer
• Format: Article
• Language: English
• Subjects: Brackish
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/BF00050743

In aquatic sediments the mineralization of organic matter regenerates phosphates, resulting in an accumulation of phosphates in the interstitial water and the formation of a concentration gradient. The subsequent diffusive transport to the overlying water is affected by chemical and microbial processes. Especially the redox state of the sediment is known to be an important factor determining the actual phosphate flux. The presence of an oxidized microlayer at the sediment surface is considered to be an important trap for phosphates. The high adsorption capacity of the oxidized microzone is generally ascribed to the presence of iron(III)-hydroxides. Lately, also the role of microorganisms has come into focus. Microorganisms in the surface layer of the sediment might act as a redox dependent source/sink mechanism of phosphates. This contribution is focused on the role of methane oxidizing bacteria in the sediment surface. In Lake Loosdrecht almost the entire methane flux diffusing upward is oxidized in the sediment surface layer. In periods with high methane production the major fraction of the oxygen consumption of the sediment can be ascribed to methanotrophic bacteria. An experimental setup will be described which enabled us to manipulate the methane flux toward the sediment surface. Microelectrode equipment was used to quantify the oxygen consumption and tThe oxygen penetration depth. In columns with high activity of methanotrophic bacteria a decrease in the oxygen penetration depth could be demonstrated. However, these columns appeared to have a higher phosphate adsorption capacity than the controls. Batch experiments were conducted to examine the role of methanotrophic bacteria in the uptake of phosphates.